MaxLength Attribute not generating client-side validation attributes

Question

I have a curious problem with ASP NET MVC3 client-side validation  I have the following class   public class Instrument   BaseObject       public int Id   get  set          Required ErrorMessage    Name is required          MaxLength 40  ErrorMessage    Name cannot be longer than 40 characters         public string Name   get  set        From my view    lt div class  editor-field  gt       Html EditorFor model   gt  model Name       Html ValidationMessageFor model   gt  model Name   lt  div gt    And here s the generated HTML I get for the textbox for this field    lt input class  text-box single-line  data-val  true  data-val-required  Name is required   id  Name  name  Name  type  text  value    gt    No sign of the MaxLengthAttribute  but everything else seems to be working   Any ideas what s going wrong

User · Answer

I had this same problem and I was able to solve it by implementing the IValidatableObject interface in my view model.

public class RegisterViewModel : IValidatableObject
{
    /// <summary>
    /// Error message for Minimum password
    /// </summary>
    public static string PasswordLengthErrorMessage => $"The password must be at least {PasswordMinimumLength} characters";

    /// <summary>
    /// Minimum acceptable password length
    /// </summary>
    public const int PasswordMinimumLength = 8;

    /// <summary>
    /// Gets or sets the password provided by the user.
    /// </summary>
    [Required]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    public string Password { get; set; }

    /// <summary>
    /// Only need to validate the minimum length
    /// </summary>
    /// <param name="validationContext">ValidationContext, ignored</param>
    /// <returns>List of validation errors</returns>
    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        var errorList = new List<ValidationResult>();
        if ((Password?.Length ?? 0 ) < PasswordMinimumLength)
        {
            errorList.Add(new ValidationResult(PasswordLengthErrorMessage, new List<string>() {"Password"}));
        }
        return errorList;
    }
}

The markup in the Razor is then...

<div class="form-group">
    @Html.LabelFor(m => m.Password)
    @Html.PasswordFor(m => m.Password, new { @class = "form-control input-lg" }
    <div class="password-helper">Must contain: 8 characters, 1 upper-case, 1 lower-case
    </div>
    @Html.ValidationMessagesFor(m => m.Password, new { @class = "text-danger" })
</div>

This works really well. If I attempt to use [StringLength] instead then the rendered HTML is just not correct. The validation should render as:

<span class="text-danger field-validation-invalid field-validation-error" data-valmsg-for="Password" data-valmsg-replace="true"><span id="Password-error" class="">The Password should be a minimum of 8 characters long.</span></span>

With the StringLengthAttribute the rendered HTML shows as a ValidationSummary which is not correct. The funny thing is that when the validator fails the submit is still blocked!

User · Answer

I know I am very late to the party  but I finaly found out how we can register the MaxLengthAttribute   First we need a validator   public class MaxLengthClientValidator   DataAnnotationsModelValidator lt MaxLengthAttribute gt        private readonly string  errorMessage      private readonly int  length        public MaxLengthClientValidator ModelMetadata metadata  ControllerContext context  MaxLengthAttribute attribute        base metadata  context  attribute                 errorMessage   attribute FormatErrorMessage metadata DisplayName            length   attribute Length             public override IEnumerable lt ModelClientValidationRule gt  GetClientValidationRules                 var rule   new ModelClientValidationRule                       ErrorMessage    errorMessage              ValidationType    length                      rule ValidationParameters  max      length          yield return rule            Nothing realy special  In the constructor we save some values from the attribute  In the GetClientValidationRules we set a rule  ValidationType    length  is mapped to data-val-length by the framework  rule ValidationParameters  max   is for the data-val-length-max attribute   Now since you have a validator  you only need to register it in global asax   protected void Application Start                      Register Validator     DataAnnotationsModelValidatorProvider RegisterAdapter typeof MaxLengthAttribute   typeof MaxLengthClientValidator        Et voila  it just works

User · Answer

lt input class  text-box single-line  data-val  true  data-val-required  Name is required        id  Name1  name  Name  type  text  value    gt       Name1   keypress function          if  this value length  gt   5  return false

User · Answer

I just used a snippet of jquery to solve this problem      input data-val-length-max    each function  index  element       var length   parseInt   this  attr  data-val-length-max          this  prop  maxlength   length         The selector finds all of the elements that have a data-val-length-max attribute set    This is the attribute that the StringLength validation attribute will set   The each loop loops through these matches and will parse out the value for this attribute and assign it to the mxlength property that should have been set   Just add this to you document ready function and you are good to go

User · Answer

In MVC 4  If you want maxlenght in input type text   You can      Html TextBoxFor model   gt  model Item3 ADR ZIP  new    class    gui-input ui-oblig    maxlength    5

User · Answer

I tried this for all the inputs in my html document textarea inputs etc  that had the data-val-length-max property and it works correctly     document  ready function              input data-val-length-max    each function  index  element            var length   parseInt   this  attr  data-val-length-max               this  prop  maxlength   length

User · Answer

Try using the  StringLength  attribute    Required ErrorMessage    Name is required      StringLength 40  ErrorMessage    Name cannot be longer than 40 characters     public string Name   get  set      That s for validation purposes  If you want to set for example the maxlength attribute on the input you could write a custom data annotations metadata provider as shown in this post and customize the default templates

User · Answer

MaxLengthAttribute is working since MVC 5 1 update  change notes

User · Answer

StringLength works great  i used it this way    StringLength 25 MinimumLength 1 ErrorMessage  Sorry only 25 characters allowed for                ProductName    public string ProductName   get  set      or Just Use RegularExpression without StringLength    RegularExpression     a-zA-Z0-9   amp    s  1 25     ErrorMessage    Reg Says Sorry only 25                     characters allowed for ProductName        public string ProductName   get  set      but for me above methods gave error in display view  cause i had already ProductName field in database which had more than 25 characters  so finally i came across this and this post and tried to validate without model like this     lt div class  editor-field  gt    Html TextBoxFor model   gt  model ProductName  new      class    form-control    data val    true    data val length    Sorry only 25 characters allowed for ProductName    data val length max    25    data val length min    1        lt span class  validation  gt   Html ValidationMessageFor model   gt  model ProductName  lt  span gt    lt  div gt    this solved my issue  you can also do validation manually using jquery or using ModelState AddModelError  hope helps someone

User · Answer

Props to  Nick-Harrison for his answer      input data-val-length-max    each function  index  element    var length   parseInt   this  attr  data-val-length-max       this  prop  maxlength   length         I was wondering what the parseInt   is for there   I ve simplified it to this with no problems        input data-val-length-max    each function  index  element        element setAttribute  maxlength   element getAttribute  data-val-length-max          I would have commented on Nicks answer but don t have enough rep yet

User · Answer

This can replace the MaxLength and the MinLength   StringLength 40  MinimumLength   10   ErrorMessage    Name cannot be longer than 40 characters and less than 10

[c#] MaxLength Attribute not generating client-side validation attributes

Examples related to c#

Examples related to asp.net-mvc

Examples related to validation

Examples related to asp.net-mvc-3

Examples related to model-validation